<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="/js/vue.js"></script>
</head>
<body>
    <div id ="app">
        <p>Frist name:<input type="text" v-model="firstName"></p>
        <p>Last name: <input type="text" v-model="lastName"></p>
        <p>fullname:{{fullname}}</p>
        <button @click="change">改变fullname</button>
    </div>
    
    <script>
       let app =new Vue({
         el:"#app",
         data:{
            firstName:'',
            lastName:''
         },
        methods:{
            change(){
                this.fullname='Harry Potter';
            }
        },
        computed:{
            fullname:{
                get:function(){
                    return this.firstName+' '+this.lastName;   
                },
                set:function(newVal){
                    let arr = newVal.split(' ');
                    this.firstName = arr[0];
                    this.lastName = arr[1];
                }
            }
        }
       })
    </script>  
</body>
</html>